German Cockroaches. How to Spot and Stop an Infestation

It is small and light brown with two dark stripes on the shield behind the head. Adults are about 1/2 inch long.¹ That puts it well below the 2 inch American roach.¹

The brownbanded roach is the lookalike. It is also about 1/2 inch, but it makes up only about 1% of indoor infestations and prefers about 80°F.¹ German roaches prefer 70 to 75°F.¹

Go back to the cockroach guide to compare all four common species, or read about the American cockroach if what you saw was large.

The female carries her egg case for most of a 30 day incubation. Each case holds about 30 young.¹ One female and her offspring can produce over 30,000 roaches in a year.¹

That is the reason a few roaches become a crowd. Across species, egg to reproducing adult takes from a few months to more than a year.¹

A good treatment has to reach every stage, which is why pros bait and then return.

Compare that with the American cockroach, whose egg case incubates about two months and holds about 12 young.¹

They hide in cracks, and an adult fits into a crack 1/16 inch wide.¹ So look for what they leave.

• Fecal specks or smears.¹
• Cast skins from molting.¹
• Egg cases.¹
• Live or dead roaches.¹

A flashlight and sticky traps find them. Put the traps where roaches are likely to walk, such as under sinks and behind appliances.^1,2 Check the traps after a few days to see which spots are busiest.

If the stripes do not match, check ceilings and the underside of furniture. Brownbanded females glue their egg cases there.¹

Indoor infestations are significant public health pests. Their allergens are linked to asthma risk in children, especially in multi unit housing.¹

German roaches can carry Staphylococcus, Streptococcus, hepatitis virus and coliform bacteria. They have been linked to typhoid and dysentery.¹

A vacuum with a HEPA filter or triple filters reduces allergens.¹ If anyone in the home has asthma, start treatment sooner.

The risk is highest in apartments and other multi unit housing.¹ If you rent, tell the landlord, since treating neighboring units together works better.³

Use baits first. Gel baits go in small dabs in cracks. They can take 7 days or longer to work. Bait stations can last for many months.¹

Add boric acid or dust in thin films in voids and under appliances. Keep dust dry, and keep boric acid indoors since it harms plants.¹ Skip foggers, bombs and aerosol sprays. UC IPM says they are generally ineffective and can scatter roaches.¹

Clean up so the bait wins. Roaches have to choose bait over other food.² Seal food, cover trash, fix leaks and wipe spills.¹

German roaches usually need a pro. Ask for a species check, bait placement in kitchen and bath, and a return visit.^1,3

German roach jobs run $200 to $400, averaging $300, because they need more intensive treatment.³ A full program of 2 to 3 visits totals $300 to $600.³

Severe infestations run $400 to $600 and typically need 3 to 4 visits.³ Quarterly prevention plans cost $100 to $175 per visit.³

Size and layout matter, since kitchens with many cabinets and appliances need more bait placements.³ In apartments, treating neighboring units together can lower the cost per unit.³

These are estimates, not quotes.³ Ask each company whether return visits are in the price.

• Store food in sealed containers and use trash cans with tight lids.¹
• Fix leaks and clean up crumbs and spills right away.¹
• Seal cracks, and add door sweeps and weather stripping.¹
• Vacuum with a HEPA filter or triple filters.¹
• Keep a regular cleaning schedule in the kitchen and bathroom.²

A one time visit does not stop new roaches. A recurring plan does more.³

• Trim shrubs, and keep a gravel strip 6 to 12 inches wide around buildings.¹
• Vacuum often and bin the bag outside.¹

There is no off season. German roaches prefer 70 to 75°F, and that is normal indoor air all year.¹ They are the most common indoor roach in California.¹

They hide by day and forage at night for food and water, so you often meet them when you flip on a light after dark.²

Cold outdoors does not matter because they live inside, in kitchens and bathrooms near food and water.

Brownbanded roaches prefer about 80°F, and males fly above 85°F.¹ Check the stripes before you buy bait.

In Ohio, anyone applying pesticides for hire on another person's property needs a commercial applicator license. The company needs a business license too.⁴ Applicators pass a core exam and at least one category exam with a 70 percent score.⁴

The license expires each Sept. 30.⁴ Apartment complexes with more than four units fall under the same rules.⁴

Renters should report roaches in writing, because roaches move between units. Treating neighboring units together can lower the price.³ See the cockroach hub for Ohio's American cockroach notes.

The German cockroach is the most common indoor roach in California.¹ UC IPM says some baits and dusts are limited to licensed applicators.¹

Structural pest control, which covers household pests, inspections and pesticide use, is regulated by the Structural Pest Control Board.⁵ Verify the company on the Board's license lookup before you sign.⁵

Read the cockroach hub for the other four California pest species.

UC IPM's bait and dust tables list which products the public can buy and which only licensed pros can use.¹ A company that treats your home for roaches should hold a license from the Board.⁵